Question

During genetic engineering, the restriction endonucleases are needed to

• A. transform the host cell
• B. ligate the foreign DNA into the host DNA
• C. produce nicks in the host DNA
• D. polymerise the vector molecule

Answer 1

Answer: (C)

Restriction endonucleases are a very important tool used in genetic engineering. These are the enzymes which make cuts (nicks) at specific positions within the double stranded DNA molecule. They recognise the palindromic base sequence in DNA duplex and introduce nicks in its strands.
For example, restriction endonuclease EcoRI recognises the base sequence GAATTC in DNA duplex and cuts the strands between G and A.